Field
Embodiments described herein are directed to techniques for locating devices.
Information
Implementation of location based services by network carriers has prompted government regulators to require “911” emergency services in that an emergency distress call from a cellular telephone are to be accompanied with an estimated location of the cellular telephone making the call. To facilitate this feature, a cellular telephone may have capabilities to estimate its own position from acquiring signals from global positioning system (GPS) satellites or from other satellite positioning systems (SPS), or from acquiring signals from terrestrial transmitters using techniques such as observed time difference of arrival (OTDOA) and/or advanced forward link trilateration (AFLT). In other examples, a location of the cellular telephone may be roughly estimated by determining a current cell that is serving the cellular telephone, and associating the known location of the serving cell with a location of the calling telephone. In yet other examples, a location of a mobile device in an indoor environment may estimate its location based, at least in part, on acquisition of signals transmitted from local transmitters (e.g., IEEE Std. 802.11 or Bluetooth transmitters).
To expand coverage for mobile telephony subscribers, wireless carrier networks have been incorporating nodes as part of a self organizing network (SON). Such nodes may comprise femto cells which may be installed by homeowners and small business owners to expand coverage where not provided by existing base stations in the wireless carrier network. Like other cellular base stations, a femto cell may support 911 emergency services.